Innova 3568 Owner's Manual page 10

Using Your Timing Light
Checking Mechanical/Centrifugal Timing Advance
1. MAKE SURE the timing light Advance Display shows 0 (zero) degrees. Press the Zeroing
Switch if necessary to obtain 0 degree indication.
2. While performing an INITIAL (BASE) TIMING CHECK as previously described, slowly increase
engine speed to the manufacturer's specified rpm for mechanical/centrifugal advance, and
observe the rotating timing mark for change. The timing mark should appear to move smoothly, in
the opposite direction of engine rotation, away from the reference pointer.
If timing mark movement is rough or erratic, the mechanical advance system may be de-fective.
Service and repair the mechanical advance system in accordance with the man-ufacturer's
instructions before continuing.
3. Press the Advance Increment and Advance Decrement switches, as necessary, until the
rotating timing mark and the reference pointer realign at the initial (base) timing mark as
previously recorded. Read the degrees of mechanical or centrifugal advance on the LCD
display. See Figure 5.
4. Note the degrees advance shown on the
LCD display, and compare this value with the
manufacturer's specification for mechanical
or centrifugal timing advance for the rpm
specified.
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If the position of the rotating timing
mark does not change during the
mechanical/centrifugal advance check,
the mechanical weights associated with
your vehicle's mechanical advance
mechanism (if equipped) may be rusted
or binding.
5. Repeat the test, as needed, for all engine
speeds specified by the manufacturer's
instructions.
Checking Vacuum Timing Advance
A vacuum pump equipped with a vacuum gauge is needed to check vacuum advance.
1. With the engine off, disconnect the vacuum hose from the distributor's vacuum advance port. Plug
the vacuum hose securely.
2. Connect the vacuum pump to the distributor's vacuum port. Do not apply vacuum at this time.
3. Start the engine and perform INITIAL (BASE) TIMING CHECK as previously described. Record
the degree(s) of initial (base) timing.
4. Using the vacuum pump, apply the manufacturer's specified amount of vacuum to the
distributor's vacuum port.
8
NOTE
Fig. 5. Advance Control Knob Operation
ADVANCE
DISPLAY
ADVANCE
INCREMENT
BUTTON
ADVANCE
DECREMENT
BUTTON
NOTE